[sdiy] BUCK stepup converter module... output goes way too high on startup !!!

[Jean-Pierre Desrochers]

Tests made on the +15vdc BUCK output :

100 ohms resistor to the GND.. no startup.. inrush current.

Even with a 1k ohms resistor to the GND the BUCK won’t settle up.

When the BUCK starts to work correctly it’s when the >30vdc output riseup starts to occurs..

 

De : The SynthiMuse <synthimuse at gmail.com <mailto:synthimuse at gmail.com> > 
Envoyé : 16 février 2024 12:05
À : Jean-Pierre Desrochers <jpdesroc at oricom.ca <mailto:jpdesroc at oricom.ca> >
Cc : Synth DIY <synth-diy at synth-diy.org <mailto:synth-diy at synth-diy.org> >
Objet : Re: [sdiy] BUCK stepup converter module... output goes way too high on startup !!!

 

Hi Jean-Pierre 

It might be a load issue. Most buck regulators need a minimum load of about 5% to 10% of their max rating. 

It could be that you're not loading it appropriately and it's struggling to establish on startup.

Not a solution, but if you give it an appropriate resistive load, it might give you an insight in to the problem.

Best wishes 

Gerry

 

 

On Fri, 16 Feb 2024, 16:50 Jean-Pierre Desrochers, <jpdesroc at oricom.ca <mailto:jpdesroc at oricom.ca> > wrote:

Hi all,

 

I’m using this type of stepup voltage regulator to generate +15vdc and +30vdc

>From an incoming single +9vdc power adapter.

These BUCK’S converters generate very good regulated voltage outputs but I noticed

that on power up they ‘need’ to rise up to around +48vdc

Before settling down to their trimmed voltages.

Well these 2 voltages will supply a DSP module @ +15vdc (not more !!!)
and a dual opamp TL072 that has a maximum allowed supply voltage of +/- 18vdc (36vdc overall).

I tried putting a 16v zener diode in parallel with the trimmed +15vdc

But the BUCK goes wild (input current rise up to around 2.5 amp and stays there !!)

I also tried to put an RC circuit at the input (33ohms + 100uf) of one of these BUCKs

But again the modules rise its input current to ‘try’ stabilize the regulation..

Even with 100ohms resistors and 16v zeners.. the BUCKs won’t start
and finalise their outputs (inrush current installs).

 

So.. I’m stuck with this problem..

Any possible solutions ???



________________________________________________________
This is the Synth-diy mailing list
Submit email to: Synth-diy at synth-diy.org <mailto:Synth-diy at synth-diy.org> 
View archive at: https://synth-diy.org/pipermail/synth-diy/
Check your settings at: https://synth-diy.org/mailman/listinfo/synth-diy
Selling or trading? Use marketplace at synth-diy.org <mailto:marketplace at synth-diy.org> 

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://synth-diy.org/pipermail/synth-diy/attachments/20240216/2ae5f8d9/attachment.htm>